Essential Questions 1.What are the characteristics of populations and how they are distributed?...
-
Upload
marjorie-aileen-hicks -
Category
Documents
-
view
224 -
download
0
Transcript of Essential Questions 1.What are the characteristics of populations and how they are distributed?...
Essential Questions1. What are the characteristics of populations
and how they are distributed?
2. What are the differences between density-independent and density-dependent limiting factors?
3. What are the similarities between the different models used to quantify the growth of a population?
4. How does carrying capacity affect reproductive rates?
Population Density
The number of organisms per unit area
Population Dynamics
Spatial Distribution
Section 1 Population Ecology
Dispersion is the pattern of spacing of a population.
Population Ecology
Population Dynamics
A species might not be able to expand its population range because it cannot survive the abiotic conditions found in the expanded region.
Population Ranges
Section 1
Population Ecology
Population-Limiting Factors
Population Dynamics
There are two categories of limiting factors—density-independent factors and density-dependent factors.
Section 1
Density-Independent Factors Any factor in the environment that does
not depend on the number of members in a population per unit area is a density-independent factor.
Population Ecology
Weather events Fire Human alterations of the landscape Air, land, and water pollution
Population Dynamics
Section 1
Density-Dependent Factors
Any factor in the environment that depends on the number of members in a population per unit area is a density-dependent factor.
Population Ecology
Biotic factors Disease Competition Parasites
Population Dynamics
Section 1
Population Biology
Population Ecology
Population Growth Rate
The population growth rate (PGR) explains how fast a given population grows.
The natality of a population is the birthrate in a given time period.
Population Dynamics
Section 1
Population Ecology
Exponential Growth Model
Exponential growth occurs when the growth rate is proportional to the size of the population.
All populations grow exponentially untilsome limiting factor slows the population’s growth.
Population Dynamics
Section 1
Population Ecology
Logistic Growth Model
The population’s growth slows or stops following exponential growth, at the population’s carrying capacity.
Population Dynamics
Section 1
Population Ecology
Population Dynamics
Section 1
A population stops increasing when the number of births is less than the number of deaths or when emigration exceeds immigration.
Population EcologySection 1
Population Ecology
Carrying Capacity
The maximum number of individuals in a species that an environment can support for the long term is the carrying capacity.
Carrying capacity is limited by the energy, water, oxygen, and nutrients available.
Population Dynamics
Section 1
Population Ecology
Reproductive Patterns
Species of organisms vary in the number of births per reproduction cycle, in the age that reproduction begins, and in the life span of the organism.
Population Dynamics
Section 1
Population Ecology
An r-strategist is generally a small organism.
Short life span
Produces many offspring
Population Dynamics
The rate strategy, or r-strategy, is an adaptation for living in an environment where fluctuation in biotic or abiotic factors occur.
Section 1
Population Ecology
A k-strategist is generally a larger organism.
Long life span
Produces few offspring
Population Dynamics
The carrying-capacity strategy, or k-strategy, is an adaptation for living in stable environments.
Section 1
Essential Questions1. What aspects affect human population
growth?
2. What are the trends in human population growth?
3. What are the age structures of representative nongrowing, slowly growing, and rapidly growing countries?
4. What might be the consequences of continued population growth?
Human Population Growth
The study of human population size, density, distribution, movement, and birth and death rates is demography.
Human Population
Population EcologySection 2
Technological Advances
For thousands of years, environmental conditions kept the size of the human population at a relatively constant number below the environment’s carrying capacity.
Population Ecology
Humans have learned to alter the environment in ways that appear to have changed its carrying capacity.
Human Population
Section 2
Human Population Growth Rate
Although the human population is still growing, the rate of its growth has slowed.
Population Ecology
Human Population
Section 2
Trends in Human Population Growth
Population trends can be altered by events such as disease and war.
Population Ecology
Human Population
Section 2
Human populationgrowth is not the same in all countries.
Zero population growth (ZPG) occurs when the birthrate equals the death rate.
Population Ecology
Zero Population Growth
The age structure eventually should be more balanced with numbers at pre-reproductive, reproductive, and post-reproductive ages being approximately equal.
Human Population
Section 2
Age Structure
Population Ecology
A population’s age structure is the number of males and females in each of three age groups:pre-reproductive stage, reproductive stage, and post-reproductive stage.
Human Population
Section 2
Human Carrying Capacity
Population Ecology
Scientists are concerned about the human population reaching or exceeding the carrying capacity.
An important factor is the amount of resources from the biosphere that are used by each person.
Human Population
Section 2